The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art. Moreover, all publications and other external materials discussed herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Expansion joints for gas and liquid conduits are known for a relatively long time, and a typical expansion joint is illustrated in U.S. Pat. No. 1,263,953. Here, the expansion joint is installed via external flanges and uses a single layer of flexible materials to accommodate for differences in length due to thermal expansion. In a similar arrangement, U.S. Pat. No. 3,460,856 teaches an externally (with respect to the internal volume of the conduit) mounted expansion joint with a composite layer of flexible material for use with high-temperature gases. To control problems associated with dust, ash, or other solid particles, U.S. Pat. No. 4,090,726 employs a baffle arrangement in a typical externally mounted expansion joint with an expansion fabric, and U.S. Pat. No. 6,027,147 discloses an internal dust seal in combination with a typical know externally mounted expansion joint.
Alternatively, in yet other known examples of known expansion joints, external sliding expansion members may be used in place of expansion fabric as shown in FR 2,274,859, and in a similar manner, U.S. Pat. No. 3,730,566 discloses use of sliding plates and an external expansion fabric. Prior Art FIG. 1 shows a typical expansion joint for a single duct. While most of the currently known expansion joints are suitable for single and relatively small ducts, significant difficulties arise where the expansion joint is intended for use with contiguous ducts, and particularly with contiguous ducts with relatively large internal diameter (e.g., smallest dimension of at least 1 m). For example, large diameter ducts 200 are often separately constructed and also separately supported on respective suitable support structures 202 as is shown in Prior Art FIG. 2A. Here, significant quantities of steel are required for the support structure 202 as well as substantial quantities of duct materials. Additionally, each duct requires its own expansion joint where such joints are needed.
To reduce the significant material cost and construction work, ducts may be configured as contiguous duct assemblies as schematically illustrated in FIG. 2B. In such case, substantial material savings can be achieved by use of a common wall element 210 between two ducts, and by providing a single support structure for the contiguous duct assembly. However, currently known expansion ducts as described above are not suitable for installation as such joints accommodate only single ducts. Therefore, to include an expansion joint, a transition or split of the ducting must be implemented to separate the contiguous duct into separate ducts that can then be fitted with the expansion joint. However, such configurations typically complicate structural support design and construction, and add significant cost.
Therefore, while numerous expansion joints are known in the art, there is still a need for improved devices and methods of expansion joints, especially for contiguous duct assemblies.